msm: mhi_dev: Add cv2x HW channel support in MHI driver

CV2X channels are used to transfer latency sensitive information
between host and modem using the IPA HW-accelerated path.

Change-Id: I3fd15de5115c4e861469f19623a7d81893020f4a
Signed-off-by: Rama Krishna Phani A <rphani@codeaurora.org>